Research On The Main Controlling Factors Of The Formation Of The Chang 8 Reservoir Of Yanchang Formation In Wuqi-Zhidan Area, Northern Shaanxi

Wuqi-Zhidan area 1s located in the central part of Yishan slope,Ordos basing secondary tectonic unit.Yanchang formation in the area discovered the Jing'an An'sai a series of scale oilfield,Changs composite layer found in many new high-yielding areas,and gained considerable control reserves,has become a hot area of Changqing oil exploration.Paper in full absorption predecessors research results and awareness of based former,to geochemical analysis technology and modern oil and gas accumulation theory for according to,integrated application large rock heart,measuring well,color quality,pressure mercury,sheet,analysis laboratory information?research area Chang8 reservoir group of source,storage,shipped,insurance conditions,established into accumulation mode,summary into accumulation main control factors.This paper analyzes and compares Wuqi-Zhidan area Chang8 two blocks and Chang81,82 reservoirs of oil enrichment differences for obvious reasons,and the reservoirs dcnsification mechanism,hydrocarbon migration dynamics,sources and main controlling factors for hydrocarbon accumulation system of analysis and research.Studies show that Chang 8 reservoir physical properties density.Porosity is nainly distributed in 4?10%,penneability is mainly distributed in less than 0.1×1O-3 range,dominated by intergranular pores,micro-throat,belonging to ultra-low permeability and low porosity reservoirs,high plastic detritus,size small,better sorting,chlorite and other fillings high,compaction and pressure solution,carbonate cementation and so on is a major factor in tight reservoir.Compaction cfrcct ot hydrocarbon generation supercharged form of abnonnal high pressure and argillite,oil migration-accumulation of main power.Research distriet exists of three sets hydrocarbon source rock,due to buried depth larger,hot evolution degree high,has reached maturel-high mature to oil and gas stage,which Chang7 mud-stone to ?-?1 type lainly.organic matter degrees high,is the area of main hydrocarbon source rock;Chang9 and Chang8 itself hydrocarbon source rock organic matter degrees relative lower,hydrocarbon capacity li,limited.Optimizing Ts C30Diahopancused tor oil-source correlation,suggested that Wu Qi Chang81 crude oil from source rocks in the overlying Chang73;Wuqi Chang82:crude oil mainly from the local Chang8,Chang9 source rocks;zhidan Chang8 oil mainly from local source rocks in Chang9,arca differences and different layers of different block sources of crude oil.The study area Zhidan,Wuqi two blocks Chang8 oil shows there are significant differences.Wuqi oil shows stable distribution,the larger;in zhidan area oil shows scattered,poor continuity,industrial output smaller.The dif"erence is mainly atreeted by sources,control of distribution of the thickness of the hydrocarbon source rock,on this basis,sand body-scale,the reservoir is also in control ot oil and gas enrichment.Research Changs storage layer is special low hole-super low infiltration storage layer,type to rock reservoir mainly,sand body up pour,sandstone lens body,typical rockreservoir accounted for most.main hydrocarbon Center control with Chang8 reservoir of distribution range;crack and permeability sand,mutual communication formed transporting system,the storage set places effect with oil of shipped moved and rich set;relative high hole high infiltration storage set sand oil rich set degree high is "dessert district".Finally through an analysis of main control factors of hydrocarbon accumulation in the study area,provide geological basis for further exploration in the area.